1. Field of the Invention
The present invention relates to a process for producing a molded ceramic or metal which is obtained by blending a resin to a ceramic powder or a metallic powder and molding the mixture into a desired configuration and then removing the resin from the molded product.
2. Description of the Prior Arts
Recently, ceramics have been widely used for various products from industrial articles to electronics parts. Severe size accuracy, physical properties and configuration accuracy of ceramic articles have been required.
It has been required to obtain desired ceramic products by blending a ceramic to a desired resin to give a plasticity and molding the mixture by an injection molding and decomposing the resin included in the molded product and firing it so as to attain the requirements. These processes have been practically applied.
The most important advantages in these processes are to prevent a formation of crackings in the molded product in an injection molding and to remove the resin without crackings, an expansion and a deformation.
Heretofore, various resin have been proposed. Styrene type resin compositions and atactic polypropylene type resin compositions have been mainly used and several kinds of the products have been proposed. Certain resin compositions have been practically used. In order to remove the resins from the molded products, it has been taken care of the treatment only by heating the molded product at a rate of elevating the temperature per unit time during several tens to several hundreds hours so as to prevent the formation of crackings, an expansion or a deformation in a molded product.
However, in spite of such cares, the crackings or the expansion are relatively easily caused in the molded product in the conventional process. These processes are not industrially satisfactory.